1. Field of the Invention
The present invention relates to the field of electrical controllers and more particularly to a novel sliding controller operated by the foot of the user for varying the resistance of a resistance element in order to adjust the volume of an electronic amplifier, loudspeaker of the like.
2. Brief Description of the Prior Art
In the past, it has been the conventional practice to adjust the volume of an amplifier used in a musical system by employing a pivotal switch or controller that varies the electrical output in accordance with an inverse proportional control. That is, as a person's foot is pressed against a pivoting lever, the resistance is changed so that the voltage output is inversely proportional to the position of the lever. Because of the angular displacement of the lever, more travel is required at the opposite ends of the control as opposed to the midsection or central portion thereof. Therefore, a musician using such a control for his amplifier does not have the advantage of a linear response along the full length of a resistor, potentiometer or the like.
Therefore, problems and difficulties have been encountered by a musician in properly adjusting the voltage for his amplifier so that it is in a linear response to the music he is playing. The sensitivity of the foot control is therefore adversely affected and is not in a true proportion to the eminating sound from loudspeakers or the like.
Therefore, there has been a long-standing need to provide a foot control for supplying amplifiers or the like with a voltage that is in direct linear proportion to the advance or retraction of a sliding member used in the potentiometer. Although rotary switches and potentiometers have been provided, such output and control is not foot-operated. It is desirable to provide a foot-operated switch which is directly proportional in its output to the linear displacement of the foot element being moved at the direction and selection of the user.